What's happening with you:

This is when you really start to notice how your body is adapting to the pregnancy, because by the end of this week your uterus will be too large to stay in your pelvis. Until now it has been sitting quite discretely under layers of tissue and bone, but your uterus is beginning to grow into your abdomen -- you may be able to feel the top, or fundus, right above your pubic bone by the end of the week. It's safe to say that your tight pants and skirts are getting rather uncomfortable, but you may also be experiencing less nausea and fatigue by now.

Although you have more blood coursing through your body and your heart is beating faster than before, you will probably experience a decrease in blood pressure during the first half of your pregnancy. This is because there will be more plasma than cells in your blood, and your blood flow fights to keep up with your increased circulation. While this won't have any effect on your general health or your baby's wellbeing, it can lead to dizzy spells and even fainting. In many cases, simply taking more time to stand up and making sure that you're eating small and frequent meals will keep you feeling strong and stable.

What's happening with your baby:

Your baby is about 2 ½ inches from crown to rump this week, and weighs anywhere between 8 and 14 grams. She's about the size of a plum now, with fully formed and functioning organ systems and distinct genitalia. While no new parts are forming, everything is maturing: fingers and toes have separated, the nervous system is developing, the small intestine has moved from the umbilical cord into her abdomen and the pituitary gland at the base of her brain is starting to produce hormones.

By now, Baby is also able to move around, open and close her mouth and clench her muscles. She reacts to little pokes and prods, but you won't be able to feel her movements yet. The amount of amniotic fluid in your uterus has increased to about 1 ½ ounces, and it will keep increasing through the months to come, helping to keep your baby safe and cushioned.

Things to do this week:

Get into good habits to ward off discomfort. Sure, there are some symptoms that you probably won't be able to avoid during your pregnancy, but careful, conscious choices will help you sidestep unnecessary pain and frustration. First, never underestimate the benefits of good posture. While you may not be supporting a huge belly yet, it's never too early to get in the habit of sitting and standing with your health in mind: pull your shoulder blades together to fight slouching, try to always distribute your weight equally between your two feet, stand tall to lengthen your neck and tighten your abdominals to keep your lower back strong.

Swelling is a common pregnancy symptom, and you might find that your feet get the worst of it. In turn, you can start your maternity wardrobe with some footwear and new additions to your sock drawer. You may want to buy new shoes that feature a wider insole in a breathable material, but avoid tall heels and completely flat styles. As for what goes between your feet and the shoes, choose cotton or wool: socks and tights made of synthetic material can leave you sweaty and uncomfortable. Maternity pantyhose have extra material to accommodate your growing belly and the waist band sits a bit higher to keep them up. Not only will these be more comfortable than your regular hose or tights, but they can also help ward off varicose veins and circulatory problems that come with restricted blood flow.

Medical musts:

If you've been longing for a glimpse of your baby-to-be, this is the week you've been waiting for! For many women, week 12 brings the first (and perhaps their only) ultrasound scan, which aims to reveal some helpful information about baby's development; the opportunity to see and hear the little life inside of you brings some excitement to the clinical exercise!

If your doctor decides that an ultrasound is appropriate, you'll have the scan performed transvaginally (using a probe inserted into the vagina) or trans-abdominally (using a transducer that is moved across the abdomen). An ultrasound, or sonogram, that's performed at this point in the pregnancy is referred to as a "basic ultrasound" and is done to locate the fetus (and ensure that you're not having an ectopic pregnancy), determine your due date, detect abnormalities (with techniques such as a nuchal translucency test) and check on your baby's condition. At this point, all of Baby's structures are formed, so you'll even be able to hear his heart beating!

The ultrasound test not only shows what's happening with your baby, it also indicates how many babies you're carrying. Multiple pregnancies can be difficult to detect through physical measurement and the severity of your pregnancy symptoms alone, because sometimes lengthy and frequent morning sickness just means you're unlucky, and a particularly large uterus can point to conditions such as molar pregnancy instead of twins. On the other hand, while multiple babies are difficult to miss and sound waves can reveal a good deal about your body and your pregnancy, remember that ultrasounds can only show so much. There is a chance that the information you get is not entirely accurate, so take any big news with a grain of salt until you can have further blood tests or ultrasounds done.

Tips for your partner:

Do what it takes to be alongside your partner in the doctor's office and relish every minute of the ultrasound. This is a big moment for her and it should be for you, too; you're both in charge of this life and this is your chance to connect with each other and your baby-to-be. It can be a bit emotional, a bit drawn out or a bit uncertain, but it will always be a special memory.

If you want to make a princely gesture for some extra brownie points, arrange to have the ultrasound picture printed and framed without mom-to-be knowing. You can also slip a copy into your pregnancy memory box or baby book as Baby's first photo. Alternatively, if your ultrasound technician can provide one, ask for a video of the ultrasound. In any case, many parents-to-be find themselves looking at the image again and again, so be sure to think ahead and plan to get your souvenir when you go in for that first sonogram.

The week's FAQs:

Will the ultrasound be painful?

Whether it's a transvaginal or a trans-abdominal ultrasound, the procedure won't cause you any pain. The wand or probe that the technician uses will send harmless sound waves through your tissue and into your uterus, where they bounce off of different structures to show size and movement. The most you'll feel is a bit of pressure, and it generally won't be too bothersome.

The one discomfort you can expect during your ultrasound exam is a full bladder. Since the bladder can obstruct the view of your uterus, you'll likely have to drink quite a bit of water before the test, which will help the bladder to lift your uterus out of the pelvis so your doctor can see it better. In this way, your bladder acts as a window to your womb, and although it may be a little uncomfortable, you'll be happy you suffered without a bathroom break when you see a clear image of your little baby for the first time.

What are my chances of having twins?

Well, this depends on a variety of factors. There's a 1 in 41 chance that you will carry multiple babies, but it's not exactly an even playing field. For instance, history counts for a lot -- if fraternal twins run in your family (usually your mother's side), you have a better chance of having them yourself, and you're about five times more likely to have a set of twins if you've already given birth to multiples. Aside from genetic factors, there's a considerably higher chance of having a multiple pregnancy when you take fertility drugs or if you are over the age of 35 when you conceive, but that only goes for fraternal twins (having identical twins is a stroke of luck).

While it can be inaccurate (and worrisome) to judge the number of babies in your belly by the symptoms you experience, there are certain characteristics that may point to twins, triplets or more. Generally, your pregnancy discomforts will be noticeably stronger or more severe and your uterus will be larger than normal at a given week. Of course, there is no guarantee that your terrible morning sickness or almost unbearable fatigue indicates more than one fetus, and you may be mistaking your extra large uterus for extra weight on your abdomen. The best way to determine whether or not you're having twins is by detecting two heartbeats via ultrasound.

We weren't able to hear the baby's heartbeat at our doctor's appointment. Should we be worried?

It is quite possible to pick up the little rhythm of baby's heart between week 10 and week 12, but there's no guarantee that your practitioner will find it. Generally, the fetal Doppler machine that's used in an ultrasound will amplify sound pretty well, but if a 12 week old fetus is in an awkward position, your placenta is interfering with the sound waves or you have a little extra abdominal fat, there's a good chance you won't be able to hear the heart beat this early.

Even with this reassurance, your eagerness to hear the heartbeat will probably occupy your mind until your next Doppler or ultrasound. If you wait until week 14 or 15, you have a much better chance of hearing it, but a 12 week ultrasound will probably reveal the fluttering beats on the screen.

Helpful hint:

An ultrasound isn't just for peeking at baby, it can actually decrease your risk of miscarriage enormously. If your doctor or midwife detects the baby's heartbeat using a transvaginal ultrasound or a Doppler after the 10 week mark, your chances of suffering a miscarriage drop to below 2%. This should bring some comfort if and when your pregnancy symptoms mysteriously disappear one day, or if you had a fall and you're worried it might have affected your baby.